Flattened like a tape, tape worms are intestinal parasites that cannot live on their own. It clings within the gut of animals, including humans. It enters the host through ingested food. It releases its egg through the feces of the host. It is very rare to find the remains of such parasites in vertebrates from the period of the dinosaurs.

The researchers analyzed coprolites or fossilized dung. Paula Dentzien-Dias and colleagues from the Federal University of Rio Grande, Brazil, unearthed the fossil in Southern Brazil, dating some 251-542 million years ago, to the Palezoic era.

The fossilized dung that was spiral-shaped belonged to a shark and had a cluster of 93 oval tapeworm eggs. Along with this coprolite, nearly 500 others were spotted at the same site. Of the 500 samples examined from this era, only one had tapeworm eggs.

According to Live Science,this new discovery predates other known examples of intestinal parasites in vertebrates by 140 million years.

According to the researchers, these fossilized eggs were found in a cluster and looked similar to those laid by a modern tapeworm.

Live Science reports that the eggs are about 150 microns long i.e., one and half times the average width of a human hair. The eggs were discovered by cutting the coprolites into thin slices. The presence of mineral pyrite in the coprolite indicates the area was depleted of oxygen. Such conditions are apt to preserve the fossilized shark for millions of years.

The details of the study were published online Wednesday in the journal PLoS ONE.